1. Field of the Invention
The present invention generally relates to an electrophotographic monochromatic copying machine capable of making a copy in one of a plurality of colors and, more particularly, to a toner cleaning device used in the copying machine.
2. Description of the Prior Art
The monochromatic copying machine referred to above is known as a copying machine capable of making a copy in one of a plurality of colors by the selective replacement of developer tanks containing toner powders of respective different colors, for example, black, red, yellow, and blue toner powders. The currently widely used copying machine capable of making a copy only in one color, for example, black color, is so designed that a quantity of residue toner removed by a blade from a photosensitive drum is recovered into the developer tank for reuse without being disposed as a waste toner. However, in the monochromatic copying machine to which the present invention pertains, no system of recovering the used toner into the developer tank is employed and the residue toner powder is disposed of into a recovery box as a waste toner, with a view to avoiding any possible mixing of a toner powder of one color with that of another and different color.
While the inclusion of even the slightest quantity of black-colored toner into a developer tank containing a mass of toner powder of color other than black results in a noticeable change in tone of the resultant copy made with the use of the toner powder of color other than black, the inclusion of a quantity of colored toner into a developer tank containing a mass of black-colored toner powder would not substantially affect the tone of the resultant copy if the quantity of the colored toner is about 5 wt %.